The present application claims priority under 35 U.S.C. xc2xa7119 of German Patent Application No. 199 10 581.2, filed on Mar. 10, 1999, the disclosure of which is expressly incorporated by reference herein in its entirety.
1. Field of the Invention
The present invention relates to a linear drive assembly used for moving a component, e.g., a cutter, and a process of using the same. Such a cutter is used, e.g., in a machine for producing or refining a fibrous material web, e.g., a paper or cardboard web, preferably at the end of such a machine in the region of a winder. The moving fibrous material web is cut crosswise to the web travel direction using the cutter, in particular when, during continuous operation, a wound roll produced on a first reel spool has become full and the forming of a new wound roll is beginning on a second reel spool, i.e., during a xe2x80x9creel spool changexe2x80x9d,
2. Discussion of Background Information
A linear drive assembly known from, e.g., German Application No. DE 27 21 883, is used for moving two cutters in opposite directions, each cutter having a circular slitting knife. The linear movement is effected by an endless cable which is driven by a friction wheel.
A device known from, e.g., U.S. Pat. No. 5,360,179, includes one or two liquid jet cutters which are moved linearly at high speed (10 m/sec) crosswise to a moving fibrous material web. Details concerning the linear drive are not described.
International Publication No. WO 97/48632 discloses a similar device, in which the linear drive has a pneumatic piston.
According to xe2x80x9cWaterjet Turn-up System,xe2x80x9d Prospectus of the Beloit Corp., a rodless cylinder serves the same purpose. The stroke speed is approximately 15.3 m/s.
Modern machines for producing or refining (or otherwise processing) fibrous material webs, e.g., paper webs, are operated at increasingly higher working speeds. In many cases, working speeds of 2000 m/min are attempted or even exceeded. Accordingly, a cutter of the type described in the introduction must also be moved crosswise to the web at an extremely high speed because, with each cutting process, at least one diagonally running cut line is made, in the region of which the paper becomes unmarketable scrap. It has always been attempted to keep the amount of scrap as small as possible.
In this regard, an even better result can be obtained with the present invention. In other words, the present invention improves the known linear drive assembly to the effect that with its use for moving a cutter of a paper machine, there is less scrap than previously.
The present invention is directed to a linear drive assembly, as generally discussed above, that also includes a device to be moved, e.g., a cutter, which is positioned in a ready (idle) position, coupled to a first high-speed thrust device that exerts an acceleration force on the device. The device is also coupled to a retaining device, which holds the device in the ready position against the acceleration force. Upon release of the retaining device, an immediate movement of the device is triggered under the action of the acceleration force mentioned. The present invention is based on the knowledge that, in many applications for a linear drive assembly, e.g., with the movement of a cutter as described in the introduction, not only is there extremely high speed, but also care must be taken that this high speed is reached in the shortest possible time at the start of the movement, That is, provision must be made for extremely high acceleration, which can be primarily accomplished with the present invention in that a ready position is provided in which the first high speed thrust device already exerts a high acceleration force on the device to be moved while in its idle position.
However, in this state according to the invention, a retaining device holds the device to be moved in its idle position. When the retaining device is released at a selected time, the high acceleration force acts on the device to be moved from the first instant. In this case, the highest speed of the device to be moved is reached in a much shorter time than with the known devices. Preferably, the retaining device can be formed as a second high-speed thrust device such that the two high-speed thrust devices work together in a practical manner as described in detail hereinbelow.
The first high-speed thrust device can preferably be a rodless pneumatic cylinder, which is of known construction its advantage lies primarily in that its length must only be slightly greater than the length of the path of the device to be moved, Moreover, because the mass to be accelerated is very small, an extremely high acceleration is yielded. In the case of a cutter of a paper machine, the length of the path of movement depends on the width of the web to be cut (e.g., on the order of 10 m).
If two cutters are provided moving in opposite directions, the length of the path is only approximately half the web width. As an alternative to a rodless pneumatic cylinder, a drive device operating on the principle of rocket propulsion could possibly be provided.
The second high-speed trust device can preferably be formed as a so-called xe2x80x9cmechanical linear unit,xe2x80x9d available, e.g., from the company NEFF Antriebstechnik Automation GmbH. An advantage of this device lies in that a very high speed of movement is possible with higher acceleration and in that acceleration and deceleration phases are readily controllable. A less advantageous alternative to be considered is a hydraulic cylinder.
The present invention is related to a linear drive apparatus that includes a movable device and a first high-speed thrust device coupled to the movable device. The first high-speed thrust device exerts an acceleration force on the movable device to move the movable device from a ready position. A movable retaining device is coupled to the movable device, so that the retaining device is adapted to hold the movable device in the ready position against the acceleration force. A release of the movable retaining device triggers immediate movement of the movable device via the acceleration force.
According to a feature of the invention, the movable device may include a cutter adapted to cut a continuous fibrous material web. The cutter can be arranged in a region of a winding machine for the continuous fibrous material web, and the first high-speed thrust device can extend cross-wise to a web travel direction.
In accordance with another feature of the instant invention, the continuous fibrous material web can include one of a paper and a cardboard web.
The first high-speed trust device can include a rodless pneumatic cylinder having a piston which is acted upon by pressure while in the ready position. The piston may be coupled to the movable device. The piston can also be permanently coupled to an interior of a pneumatic pressure tank.
Further, a second high-speed thrust device which can include the retaining device. The second high-speed thrust device can further include at least one deflecting device and a flexible line coupled to the at least one deflecting device. One end of the flexible line can be coupled to the movable device and the other end of the flexible line can be held stationary. In this way, the flexible line may be under tension in the ready position. The movable device can include a fluid jet cuter having at least one fluid jet nozzle, and the flexible line can include a high-pressure hose line coupled to supply cutting fluid to the fluid jet cutter The second high-speed thrust device can include a mechanical linear unit having a linearly movable element coupled via a toothed belt to a drive motor.
According to still another feature of the invention, the movable device can include a part of a laser beam cutter.
In accordance with a further feature of the invention, one of a stroke speed and a stroke acceleration of the first high-speed thrust device may be at least twice a corresponding one of a stroke speed and a stroke acceleration of the second high-speed thrust device. Further, the one of the stroke speed and stroke acceleration of the first high-speed trust device can be assisted by a deflecting roll.
The invention is directed to a reel spool changing apparatus for a continuously operating one of a web producing and refining machine. The apparatus includes two cutters which are movable in opposite directions to cut the web, and two first high-speed thrust devices, arranged in cross-wise directions to the web, coupled to the two cutters. The first high-speed thrust devices exert an acceleration force on the two cutters to move the two cutters from a ready position. Two movable retaining devices are coupled to the two cutters, and the retaining devices are adapted to hold the two cutters in their ready positions against the acceleration forces. A release of the movable retaining devices triggers immediate movement of the two cutters via the acceleration force.
According to a feature of the present invention, the two cutters may include high-pressure fluid jet nozzles. Further, the high-pressure fluid jet nozzles may exert a fluid pressure at least in a range between approximately 1000-2000 bar. Still further, the first high-speed thrust devices may include rodless cylinders having pistons coupled to the two cutters. Moreover, second high-speed thrust devices can include the movable retaining devices. The second high-speed thrust devices can firer include cylinder/piston devices having piston rods, and the piston rods may be coupled to the movable retaining devices. Alternatively, the second high-speed thrust devices can further include movable elements coupled to driven belts, and the movable elements may be coupled to the movable retaining devices.
The instant invention is directed to a linear drive apparatus for driving cutting assembly in a region of a web winding device. The apparatus includes at least one movable device comprising a cutting device, and first high-speed thrust devices respectively coupled to each the movable device. The first high-speed thrust devices exert an acceleration force cross-wise to a web run direction on tie movable devices to move the movable device from a ready position. Movable retaining devices are respectively coupled to each the movable device, and the retaining devices are adapted to hold the movable devices in the ready position against the acceleration force. The first high-speed thrust devices include a rodless pneumatic cylinders having pistons which are acted upon by pressure while in the ready position, and the pistons are respectively coupled to each the movable devices. Second high-speed thrust devices include the retaining devices. A release of the movable retaining devices triggers immediate movement of the movable devices via the acceleration force.
The present invention is directed to a process of cutting a material web in a region of a winding machine with a cutting device driven by a linear drive that includes a movable device coupled to a cutter, a first high-speed thrust device coupled to the movable device, and a movable retaining device coupled to the movable device. The process includes positioning the movable device in an idle position, holding the movable device in the idle position with the retaining device, exerting an acceleration force on the movable device while it is being held in the idle position, actuating the cutter to cut the web while the movable device is held in the idle position, and releasing the movable device from the idle position by moving the retaining device. In this manner, the acceleration force moves the moving device.
In accordance with a feature of the present invention, the process can further include actuating the cutter to cut the web while the movable device is held in the idle position,
According to yet another feature of the invention, the acceleration force can be directed cross-wise to a web run direction.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing,